Thing Statistics

Summary

Tired of trying to align Z threaded rods and get rid of wobble I created X mounts that absorbs XY movements that Z threaded rods cause when not perfectly aligned. The absorbing structures use same principle of some lunar rover wheels. The structure uses ABS flexibility as absorber.http://youtu.be/XAVHZ00X4DM

Instructions

On Z threaded rods, to limit vertical movement of nuts it's necessary to glue and small lid over upper nut. Inside use the common nut spring nut system.

The part I printed got a little bit fragile, I have to do some improvements but works great!

Thanks, I did not model this spring mathematically. The equation would have a lot of variables as wall thickness, height, total lengthand material elastic properties. Even your print parameters will change behavior. I suggest you an empirical approach, manipulating variables listed above to get the perfect spring for your application.

even if your rods are perfectly aligned, they could still be bent slightly. by using the springs in the way they are printed, they let the smooth rods make the axis move in only one direction, by only accepting one axis of motion from the leadscrews. i plan to use a design similar to this in my printer.

You can try that, but I recommend to use the 2 nuts per rod with spring between system. About spring, I can assure you there is no sign of fatigue(white spots) on my springs. I printed them with a 0.35mm nozzle, and with this thickness the spring printed with 2 layer wall. For a bigger nozzle I would thicken proportionally. But thickening will reduce flexibility. You can also play different spring lengths and check the results.

The problem you're trying to solve is because you're over-binding your threaded rods. Â Those bearings at the bottom of the machine are BAD BAD BAD. Â Take them out, and replace your rod couplers with the good aluminum ones. Â This allows the threaded rod to move in the X/Y as opposed to moving your carriage instead. Â You want the Z threaded rods to be loose so that the smooth rod can take over.

Â Actually the bottom bearings are not bad, if you can get straight rod and center the upper coupling - it offloads weight of the X assembly from the stepper bearings, which are not actually suited for the task.

Thantik thanks Â for the tips!I've been convinced to solve the problem on its cause.You are right about bottom bearings, I 'll remove it.
I do have aluminum couplers. In the video I was testing one side with with tubes, and it seems tube did a better job. The aluminum coupler have one issue that is: Screwing over threads, that won't allow a goodÂ alignment.Â

Updating: After releasing threaded rod from bottom bearing the spring still moves, but with a smaller amplitude. So it still acts and isÂ contributingÂ a little to increase precision.Â Of courseÂ coupling is not perfect, but it will never be

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